This invention relates to enclosing and sealing a substrate, such as a plurality of wires or a splice between two or more wire, and to an assembly comprising a heat recoverable article for effecting such sealing.
When two or more insulated wires are spliced together, the insulation is generally removed from the section of the wires which are to be joined together by soldering, crimping, or the like. After the wires have been spliced it is desirable to insulate the splice area, that is the entire area of the splice and adjacent bared wires. This entire area is referred to herein as the splice. The splice area may also include an electrical component such as a fuse, diode or transistor or the like spliced to the wires. It is also desirable to seal the area between adjacent wires of a splice, wire bundle or cable to prevent ingress of water, solvents or other contaminants and migration of such contaminants along the insulation of the individual wires.
Various approaches have been proposed to insulate and seal splices and wire bundles. One approach has been to use a heat recoverable tubular article, optionally coated with a hot melt adhesive or sealant. This requires access to a free end of the wires and installation of the recoverable tubing before the wires are spliced. After the wires are spliced, the tubing is slid over the splice and heat is applied to cause recovery of the tubing and to cause the adhesive or sealant to melt and flow. An example of such a heat recoverable tubular article is sold commercially by Raychem Corporation under the trademarks "FLT", "SCT" and "MVT".
At times it is not convenient or feasible to install the recoverable tube over the wires, particularly when three or more wires are involved or a branch is joined to another wire. The use of a heat recoverable wrap-around article has been proposed for example in U.S. Pat. Nos. 3,847,721 to Evans and 3,899,807 to Sovish. Evans discloses articles rendered involutely heat recoverable by differentially annealing a molecularly oriented unitary polymeric layer so as to provide an anisotropic gradient through the thickness thereof. Sovish et al discloses articles rendered involutely heat recoverable by lamination of a first heat recoverable layer to a second, relatively non-heat recoverable layer which resists linear recovery of the first such that the laminated article curls upon recovery. It is believed that the Evans and Sovish et al articles have not met with commercial success primarily due to the circumstance that it is difficult to control the final shape of the article.
Another device which is recoverable to form an enclosing tube is Foley U.S. Pat. No. 3,483,285. The device is used as a clamp for encircling wires or cables. Glasgow U.S. Pat. No. 3,620,896 also discloses a cable clamp. The use of an adhesive to bond the wraparound article to itself and to the underlying substrate is mentioned. A wrap-around recoverable article particularly suitable for use as a marker sleeve is disclosed in commonly assigned copending application Ser. No. 877,620 filed Feb. 9, 1988 by Hansen et al, the entire disclosure of which are incorporated herein by reference. Other wrap-around articles are disclosed in U.S. Pat. Nos. 2,138,568 to Brauduberger and 3,416,991 to Yoshimura and British Patent No. 1,091,588 to Toyoba.
None of these references address the problem of sealing a plurality of wires or a splice.